source/cpu: detect SST-BF

Detect of the Intel SST-BF (Speed Select Technology - Base Frequency)
has been enabled.

Adds one new feature label:
  feature.node.kubernetes.io/cpu-power.sst_bf.enabled=true

Based on a patch from kuralamudhan.ramakrishnan@intel.com

README.md

@@ -213,9 +213,10 @@ discovers CPU related features that are actually enabled, whereas CPUID only
 reports *supported* CPU capabilities (i.e. a capability might be supported but
 not enabled) as reported by the `cpuid` instruction.
 
-| Feature name            | Description                                        |
-| ----------------------- | -------------------------------------------------- |
-| hardware_multithreading | Hardware multithreading, such as Intel HTT, enabled (number of locical CPUs is greater than physical CPUs)
+| Feature                 | Attribute      | Description                       |
+| ----------------------- | -------------- | ----------------------------------|
+| hardware_multithreading | <br>           | Hardware multithreading, such as Intel HTT, enabled (number of locical CPUs is greater than physical CPUs)
+| power                   | sst_bf.enabled | Intel SST-BF ([Intel Speed Select Technology][intel-sst] - Base frequency) enabled
 
 ### X86 CPUID Features (Partial List)
 
@@ -643,6 +644,7 @@ A demo on the benefits of using node feature discovery can be found in [demo](de
 [cpuid]: http://man7.org/linux/man-pages/man4/cpuid.4.html
 [intel-rdt]: http://www.intel.com/content/www/us/en/architecture-and-technology/resource-director-technology.html
 [intel-pstate]: https://www.kernel.org/doc/Documentation/cpu-freq/intel-pstate.txt
+[intel-sst]: https://www.intel.com/content/www/us/en/architecture-and-technology/speed-select-technology-article.html
 [sriov]: http://www.intel.com/content/www/us/en/pci-express/pci-sig-sr-iov-primer-sr-iov-technology-paper.html
 [docker-down]: https://docs.docker.com/engine/installation
 [golang-down]: https://golang.org/dl

source/cpu/cpu.go

@@ -17,13 +17,17 @@ limitations under the License.
 package cpu
 
 import (
-	"fmt"
 	"io/ioutil"
+	"log"
 	"path"
 
 	"sigs.k8s.io/node-feature-discovery/source"
 )
 
+const (
+	cpuDevicesBaseDir = "/sys/bus/cpu/devices"
+)
+
 // Implement FeatureSource interface
 type Source struct{}
 
@@ -35,24 +39,32 @@ func (s Source) Discover() (source.Features, error) {
 	// Check if hyper-threading seems to be enabled
 	found, err := haveThreadSiblings()
 	if err != nil {
-		return nil, fmt.Errorf("Failed to detect hyper-threading: %v", err)
+		log.Printf("ERROR: failed to detect hyper-threading: %v", err)
 	} else if found {
 		features["hardware_multithreading"] = true
 	}
+
+	// Check SST-BF
+	found, err = discoverSSTBF()
+	if err != nil {
+		log.Printf("ERROR: failed to detect SST-BF: %v", err)
+	} else if found {
+		features["power.sst_bf.enabled"] = true
+	}
+
 	return features, nil
 }
 
 // Check if any (online) CPUs have thread siblings
 func haveThreadSiblings() (bool, error) {
-	const baseDir = "/sys/bus/cpu/devices"
-	files, err := ioutil.ReadDir(baseDir)
+	files, err := ioutil.ReadDir(cpuDevicesBaseDir)
 	if err != nil {
 		return false, err
 	}
 
 	for _, file := range files {
 		// Try to read siblings from topology
-		siblings, err := ioutil.ReadFile(path.Join(baseDir, file.Name(), "topology/thread_siblings_list"))
+		siblings, err := ioutil.ReadFile(path.Join(cpuDevicesBaseDir, file.Name(), "topology/thread_siblings_list"))
 		if err != nil {
 			return false, err
 		}

source/cpu/power_amd64.go

@@ -0,0 +1,76 @@
+/*
+Copyright 2018 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package cpu
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path"
+	"strconv"
+	"strings"
+
+	"sigs.k8s.io/node-feature-discovery/pkg/cpuid"
+)
+
+const (
+	// CPUID EAX input values
+	LEAF_PROCESSOR_FREQUENCY_INFORMATION = 0x16
+)
+
+func discoverSSTBF() (bool, error) {
+	// Get processor's "nominal base frequency" (in MHz) from CPUID
+	freqInfo := cpuid.Cpuid(LEAF_PROCESSOR_FREQUENCY_INFORMATION, 0)
+	nominalBaseFrequency := int(freqInfo.EAX)
+
+	// Loop over all CPUs in the system
+	files, err := ioutil.ReadDir(cpuDevicesBaseDir)
+	if err != nil {
+		return false, err
+	}
+	for _, file := range files {
+		// Try to read effective base frequency of each cpu in the system
+		filePath := path.Join(cpuDevicesBaseDir, file.Name(), "cpufreq/base_frequency")
+		data, err := ioutil.ReadFile(filePath)
+		if os.IsNotExist(err) {
+			// Ignore missing file and continue to check other CPUs
+			continue
+		} else if err != nil {
+			return false, err
+		}
+
+		effectiveBaseFreq, err := strconv.Atoi(strings.TrimSpace(string(data)))
+		if err != nil {
+			return false, fmt.Errorf("non-integer value of %q: %v", filePath, err)
+		}
+
+		// Sanity check: Return an error (we don't have enough information to
+		// make a decision) if we were able to read effective base frequency,
+		// but, CPUID didn't support frequency info
+		if nominalBaseFrequency == 0 {
+			return false, fmt.Errorf("failed to determine if SST-BF is enabled: nominal base frequency info is missing")
+		}
+
+		// If the effective base freq of a CPU is greater than the nominal
+		// base freq, we determine that SST-BF has been enabled
+		if effectiveBaseFreq/1000 > nominalBaseFrequency {
+			return true, nil
+		}
+	}
+
+	return false, nil
+}

source/cpu/power_stub.go

@@ -0,0 +1,23 @@
+// +build !amd64
+
+/*
+Copyright 2018 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package cpu
+
+func discoverSSTBF() (bool, error) {
+	return false, nil
+}